An 18-bit high performance audio σ-δ D/A converter

A multi-bit quantized high performance sigma-delta (σδ) audio DAC is presented. Compared to its singlebit counterpart, the multi-bit quantization offers many advantages, such as simpler σδ modulator circuit, lower clock frequency and smaller spurious tones. With the data weighted average (DWA) mismatch shaping algorithm, element mismatch errors induced by multi-bit quantization can be pushed out of the signal band, hence the noise floor inside the signal band is greatly lowered. To cope with the crosstalk between digital and analog circuits, every analog component is surrounded by a guard ring, which is an innovative attempt. The 18-bit DAC with the above techniques, which is implemented in a 0.18 μm mixed-signal CMOS process, occupies a core area of 1.86 mm2. The measured dynamic range (DR) and peak SNDR are 96 dB and 88 dB, respectively. © 2010 Chinese Institute of Electronics.